More than 150 of the world's foremost academics have intervened in a simmering row over the banning of debates on the Israel-Palestine question at one of France's universities, calling the move a threat to free speech.

Professors and intellectuals from Britain, the US and Canada, including American philosopher Noam Chomsky, signed a petition calling on the Ecole Normale Supérieure (ENS) in Paris to restore "its long history of free speech and political expression".

The row erupted after group of students calling itself the ENS Palestine Collective invited the bestselling writer Stéphane Hessel, 93, to a debate on the alleged criminalisation of supporters of the boycott of Israel in January.

Hessel is author of Indignez-Vous! (Time for Outrage) in which he expresses his belief in universal rights and criticises Israel's treatment of Palestinians.

As well as Hessel, the Palestine Collective also invited a former French justice minister, two Israeli pacifists and the Palestinian representative in Europe.

Less than a fortnight before the event, the university director, Monique Canto-Sperber, withdrew permission for the event. A few weeks later, she refused permission for a Palestine Collective-organised conference as part of "Israel Apartheid Week". When her decision was applauded by a group of Jewish organisations, the Palestine Collective - a group of 15 students and teachers - accused her of bowing to pressure.

A Paris court struck down her ruling, but a higher court upheld it, arguing that higher education must be "independent of all political, economic, religious or ideological influence".